The odds are generally known to the wager when he places a bet on a particular sports event.
This category of odd known only at the beginning of the match is known as starting prices. The price up of over 100% indicates more profit to the bookmaker and hence they will always prefer such type of odds and is called a balanced book. In the case of imbalanced book the bookmaker may have more winners than losers and have a chance to lose his money and in certain situations may get more than expected from the result of a match.
The evolution of internet gave rise to arbitrage in fixed odds against the bookmakers.
The operations of sports betting take place in a bet exchange which is similar to that of a stock exchange. Online betting allows anyone to place their bet on these exchanges through any registered bookmakers. This allows an easy platform to set the odds which are almost equal to the true odd in the market. When betting, a person should expect a positive value in his odd. But incase you get a chance to select odd from 10 to 1 from a set of 52 cards your chances to win are grim. So odds must be chosen carefully.
The person making a bet expects to win and is placing the odd or bet. If you place a bet on the weather on $1000 expecting that it will rain tomorrow. If you win you will get $1200. In actual situation you are gaining only $200 on the bet at a risk of $1000 if you fail. You may get either side of the coin. Placing a bet does not mean that you will fail, there is chance that you might win. There are many types of odd found in the betting market like fractional odds, decimal odds, money line odds, positive figures and negative figures.